The present embodiments relate to a device for power measurement on a power amplifier of a magnetic resonance device.
In the case of a magnetic resonance device, a power amplifier may be employed in order to generate high frequency power to excite nuclear spin. For transmission, the power amplifier is coupled to a transmit antenna (e.g., a whole-body antenna), to which a switching device may be provided. If the antenna is also used as a receive antenna, the switching device may, for example, be embodied to couple the antenna optionally with the power amplifier and a receiver device.
For example, when a live patient is examined with the magnetic resonance device, but also if a loss check is to take place, a power measurement device may be employed for measurement of the forward power, which may be connected via a directional coupler downstream of the switching device. Whether the correct power is being radiated may be checked before the transmit antenna, and samplings in relation to a specific absorption rate (SAR) may be activated.
If samplings for SAR are also to be activated with the primary power device, the measured values of the primary power measurement device may be relied on. A secondary power measurement device between the output of the power amplifier and the switching device (e.g., directly downstream of the output of the power amplifier, which is linked via a directional coupler). Consistency checks may thus be performed between the measurements, or the primary power measurement device may be calibrated. It is known, for example, to carry out a calibration of the primary power measurement device at regular intervals.